The following ICD-10 codes were assessed as outcomes: intracranial laceration and haemorrhage due to birth injury (P10), intracranial non-traumatic haemorrhage of foetus and newborn (P52), convulsions of newborn (P90), and other disturbances of the cerebral status of the newborn; encephalopathy (P91). The definition of each outcome is described in detail in Table 1. Infants that had at least one outcome diagnosis in The Swedish Medical Birth Register or in the Swedish National Inpatient Register were counted as cases. More than 85% of the outcome diagnoses were retrieved from the Swedish Medical Birth Register and 15% came from the Swedish National Inpatient Register. The registers do not cover information on when an infant was diagnosed.